EP3774040A1 - Commande de processus évolué dans un reformeur à régénération catalytique continue - Google Patents

Commande de processus évolué dans un reformeur à régénération catalytique continue

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Publication number
EP3774040A1
EP3774040A1 EP18911402.8A EP18911402A EP3774040A1 EP 3774040 A1 EP3774040 A1 EP 3774040A1 EP 18911402 A EP18911402 A EP 18911402A EP 3774040 A1 EP3774040 A1 EP 3774040A1
Authority
EP
European Patent Office
Prior art keywords
advanced process
process controller
controller
regenerator
reactor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP18911402.8A
Other languages
German (de)
English (en)
Other versions
EP3774040A4 (fr
Inventor
Kondapalli Shreya CHAUDHARY
Shashi Kant SHUKLA
V. Suresh
Susanta SADHUKHAN
Jitendra Kumar Verma
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bharat Petroleum Corp Ltd
Original Assignee
Bharat Petroleum Corp Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bharat Petroleum Corp Ltd filed Critical Bharat Petroleum Corp Ltd
Publication of EP3774040A1 publication Critical patent/EP3774040A1/fr
Publication of EP3774040A4 publication Critical patent/EP3774040A4/fr
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/0006—Controlling or regulating processes
    • B01J19/0033—Optimalisation processes, i.e. processes with adaptive control systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/02—Heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J38/00—Regeneration or reactivation of catalysts, in general
    • B01J38/04—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst
    • B01J38/42—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst using halogen-containing material
    • B01J38/44—Gas or vapour treating; Treating by using liquids vaporisable upon contacting spent catalyst using halogen-containing material and adding simultaneously or subsequently free oxygen; using oxyhalogen compound
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/001—Controlling catalytic processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G35/00—Reforming naphtha
    • C10G35/04—Catalytic reforming
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G35/00—Reforming naphtha
    • C10G35/24—Controlling or regulating of reforming operations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/10—Feedstock materials
    • C10G2300/1096—Aromatics or polyaromatics
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
    • C10G2300/40—Characteristics of the process deviating from typical ways of processing
    • C10G2300/4081—Recycling aspects

Definitions

  • the present invention relates to an advanced process control system for a continuous catalytic regeneration reformer where a reactor advanced process controller and a regenerator advanced process controller are linked to a master advanced process controller.
  • a typical process unit has a certain basic process controls which are designed and built, to facilitate basic operation, control and automation requirements. These process controls encompass stand-alone flow, level, pressure and temperature loops and are typically called closed loops in a Distributed Control System (DCS).
  • DCS Distributed Control System
  • An advanced process control (APC) takes many such standalone loops into a single control execution environment. Also APC is capable of taking open loops into the same control environment.
  • octane of naphtha (IBP- 180 °C cut hydrocarbon) feed is augmented to meet the requirement of the refinery gasoline pool.
  • the CCR process also involves a continuous circulation or movement of the catalyst from the reactors to the regenerator, back to the reactors and so on.
  • the catalyst changes atmosphere from hydrogen-hydrocarbon, to small amount of oxygen in a nitrogen carrier gas for carbon burn, higher oxygen for proof bum, and much higher oxygen to re-disperse the noble metals in a high chloride environment. Therefore, catalyst regeneration in a reforming unit is a multi-interactive system and it is possible to control it. However, consistent optimization of the catalyst regeneration is humanly an impossible task.
  • US7291311B2 describes an improvement in operation of catalyst circulation to make the function of the regeneration zone more stable and safer, and also to improve the overall performances by anticipating deviations, will be able to function with a lower average amount of coke deposited on the catalyst. Further, the patent describes automatic control of combustion zone in a catalyst reforming or fluidized bed process.
  • US9701914B2 describes an advanced control of severe fluid catalytic cracking process for maximizing propylene production from petroleum. However, the patent does not describe implementation of the advanced control system for catalyst regeneration.
  • Catalytic Naphtha Reforming A Novel Control System for the Bench-Scale Evaluation of Commercial Continuous Catalytic Regeneration Catalysts; Enrico Caricato, et. al.; Sasol group, describes an automated control system for the bench-scale evaluation of CCR naphtha reforming catalysts.
  • the literature describes that a multivariate model between heater temperatures and catalyst bed temperatures was constructed and an APC loop was designed for setting desired catalyst bed temperatures during the tests.
  • the present invention as embodied and broadly described herein discloses use of master - slave (M-S) concept, within an advanced process controller (APC) design to control coke on spent catalyst while maximizing heavy reformate octane barrel using online inferential, both for coke content of spent catalyst and octane of heavy reformate.
  • M-S master - slave
  • API advanced process controller
  • an aspect of the present invention is to provide an APC system for a continuous catalytic regeneration (CCR) reformer comprising of a M-S configuration, which further comprises a master APC, a reactor APC, and a regenerator APC, wherein, the reactor APC and the regenerator APC are linked to the master APC.
  • CCR continuous catalytic regeneration
  • the controller would not observe the effect of manipulation of reactor severity on the coke content of spent catalyst.
  • the APC of the present invention are designed to maximize octane barrel of heavy reformate while maintaining the coke on spent catalyst. All possible constraints have been incorporated within the APC so that they are robust, do not require manual intervention to look at any aspect of the process, making them sustainable. Manipulation of a number of variables, by APC, provides more degrees of freedom to control the process within the operating window.
  • interlocks have been incorporated in the present invention in order to build in intelligence within the APC, to take conducive action, to avoid reverse action, to change the control from supervisory to supervisor in case of plant exigencies.
  • a number of small advanced process controllers have been conceived instead of one big one. This avoids the possibility of all the process parameters being out of the control window, at the same time, in case of any erroneous indication / any section of the plant being upset or shut down.
  • Fig. 1 illustrates the concept of reformer master - slave advanced process controller
  • Fig. 2 illustrates the reformer master advanced process controller design
  • Fig. 3 illustrates the reformer reaction section (slave 1) advanced process controller design
  • Fig. 4 illustrates the reformer regeneration section (slave 2) advanced process controller design
  • Fig. 5 illustrates the reformer reaction section (master) advanced process controller design
  • Fig. 6 illustrates the reformer reaction section (slave) advanced process controller design
  • Fig. 7 illustrates the sustained operation of reformer at a lower reactor weighted average inlet temperature due to the advanced process controller operation
  • Fig. 8 illustrates the sustained optimization in reformer fired heaters operation with respect to the tube skin temperature due to the advanced process controller operation
  • Fig. 9 illustrates the sustained operation of the reformer reaction section fired heater at a lower fuel fired due the advanced process controller operation
  • Fig. 10 illustrates the sustained operation of the reformer at a lower hydrogen to hydrocarbon ratio due to the advanced process controller operation
  • Fig. 11 illustrates the sustained operation of the reformer recycle gas compressor at a lower speed due to the advanced process controller operation
  • Fig. 12 illustrates the sustained operation of the reformer recycle gas compressor at a lower steam consumption due to the advanced process controller operation
  • Fig. 13 illustrates the sustained operation of reformer at a higher catalyst circulation rate due to the advanced process controller operation
  • Fig. 14 illustrates the sustained operation of the regenerator I st bed at a higher carbon burning rate due to the advanced process controller operation
  • Fig. 15 illustrates the sustained operation of the regenerator 2 nd bed at a certain minimum carbon burning rate due to the advanced process controller operation
  • Fig. 16 illustrates the sustained operation of the regenerator oxychlorination zone at a higher temperature due to the advanced process controller operation
  • Fig. 17 illustrates the operation of the regenerator calcination zone at a higher temperature due to the advanced process controller operation
  • Fig. 18 illustrated the sustained operation of the reduction chamber at the desired temperature due to the advanced process controller operation
  • Fig. 19 illustrates the sustained operation of the regenerator calcination zone at a higher oxygen content due to the advanced process controller operation
  • Fig. 20 illustrates the controller of the reformer recycle gas moisture in the desired range due to the advanced process controller operation
  • Fig. 21 illustrates the sustained operation of reformer at much lower lift velocities due to the advanced process controller operation
  • Fig. 22 illustrates the complete block diagram of the CCR reforming process
  • the present invention relates to an advanced process control (APC) system for a continuous catalytic regeneration (CCR) reformer where a reactor APC and a regenerator APC are linked to a master APC. Further, the present invention relates to the application of APC systems to CCR reformer in order to maximize octane barrel of heavy reformate while maintaining the coke on spent catalyst.
  • APC advanced process control
  • CCR continuous catalytic regeneration
  • an APC system for a CCR reformer comprising of a master-slave configuration (M-S configuration), wherein the M-S configuration comprises of a master APC, a reactor APC, and a regenerator APC, and wherein the reactor APC and the regenerator APC are linked to the master APC.
  • M-S configuration master-slave configuration
  • the reactor APC and the regenerator APC are linked to the master APC.
  • a general CCR reforming process involves:
  • operating parameters in the reactor section are controlled by the reactor APC and operating parameters in the regenerator section are controlled by the regenerator APC. Further, the reactor APC and the regenerator APC are linked and controlled by the master APC.
  • hydrotreated naphtha from naphtha hydro treater unit after mixing with recycle gas, preheating and final heating in the feed effluent exchanger and charge heater respectively is fed to I st reactor in a series of four reactors (RI to RIV) to obtain reactor effluent.
  • RI to RIV reactor effluent
  • inter heaters are provided in between the reactors to maintain desired reactor inlet temperature.
  • the CCR is designed to produce octane rich motor spirit blend component - the heavy Reformate and benzene and toluene rich middle reformate.
  • the reactor effluent after exchanging heat in the feed effluent exchanger is cooled in the trim condenser and sent to a separator.
  • a desired quantity of gas is then recycled to the reactor section using a recycle gas compressor and the net gas is sent to the re-contacting section.
  • a cryogenic recovery system is used to maximize hydrogen and liquefied petroleum gas (LPG) production while a Pressure Swing Adsorber (PSA) unit is used to recover hydrogen from the net gas.
  • Stabilizer overhead liquid is stabilized in a Debutanizer and is then routed to LPG storage bullets.
  • Stabilized reformate is split in a reformate splitter to get desired middle (benzene and toluene rich cut) and heavy (motor spirit blend component) reformate along with a paraffin rich light reformate stream which can be routed to naphtha or motor spirit pool.
  • the reaction section APC controls the process parameters across the four reactors, intermediate fired heaters (H! to HIV), separator (SEP), recycle gas compressor (RGC), net gas (HP) compressors etc. shown in Fig. 22a.
  • CCR Regeneration section provides a continuous stream of clean, coke-free active catalyst that is recycled back to the reactors. Continuous circulation of regenerated catalyst helps to maintain optimum catalyst performance at high severity for long on stream periods.
  • the regeneration section APC controls the process parameters in the regeneration circuit comprising of the regenerator, lower hoppers (low hop), lift pots, upper hoppers (up hop), reactors (RI to RIV), reduction chamber (red cham) etc. as shown in Fig. 22b.
  • a typical APC works on the concept of controlled variables, manipulative variable, and disturbance variables.
  • the control variable means variable that need to be controlled
  • the manipulative variable means variable that can be manipulated to control the process
  • the distributed variable means the variable that cannot be controlled, like the ambient temperature etc. but affects the process plant.
  • the slave element of the M-S configuration comprises of the reactor APC and the regeneration APC.
  • the slave element of the present invention is also called slave APC or slave controller and the terms are used interchangeably throughout the description.
  • the master APC is also called as master controller and is used interchangeably throughout the disclosure.
  • the master APC is also called as coke controller, as shown in Fig. 2 of the present invention and is used interchangeably throughout the disclosure.
  • the reactor APC is also called as reactor controller
  • the regeneration APC is also called as regeneration controller
  • the master APC is also called master controller and the terms are used interchangeably throughout the description.
  • the slave elements i.e. the reactor controller and the regenerator controller are full-fledged APCs having their own controlled variables to control and alter their parameters based on their own controlled variables.
  • the slave controller is also a master controller of the reactor section.
  • the slave controller is also a master controller of the regeneration section.
  • Fig. 1 shows the M-S configuration of the present invention, wherein the master controller is linked to both the reactor controller and the regenerator controller.
  • the reforming is optimum at a certain coke on the spent catalyst.
  • the APCs vary the reformer operating severity, the Hydrogen/Hydrocarbon ratio (H 2 /HC) etc. to keep the reforming plant operation optimized. These changes impact the coke on the catalyst at the outlet of the last reactor i.e. on the spent catalyst.
  • the master APC of the present invention maintains an optimum coke on spent catalyst by manipulating the H 2 /HC ratio and the catalyst circulation rate and further achieves the same through M-S configuration.
  • the coke controller gives a set point to the slave APC in the reaction section and the regeneration section. More particularly, the set point of the H 2 /HC ratio is passed on from the master controller to the reactor controller; while the set point of the catalyst circulation is passed on from the master controller to the regenerator controller.
  • the H 2 /HC ratio and catalyst circulation ratio are manipulated variables and coke on the spent catalyst is controlled variable in the M-S configuration, as shown in Fig. 2 of the present invention.
  • the master controller is executed every 10 minutes unlike a typical APC which is executed every minute. This ensures that the slave APC have had enough time to implement the desired change.
  • the slave APCs are executed every minute.
  • the M-S configuration enables the master controller to execute every 10 minutes and enables the reactor controller and the regeneration controller to execute every minute.
  • the reactor controller acts as a master controller, further called as reaction section master controller or reaction master controller and has another slave controller, further called as reaction section slave controller or reaction slave controller.
  • the reformer reaction section master controller generates a target Weighted Average Inlet Temperature (WAIT) based on its dependent (controlled) variable, heavy reformate octane barrel and the set point of the separator pressure. Therefore, in the reaction master controller ‘WAIT’ is an independent variable.
  • WAIT Weighted Average Inlet Temperature
  • the master controller is linked to the reactor controller, such that the manipulated variable H 2 /HC ratio of the master controller is connected to the reaction section slave controller.
  • the reactor controller optimizes the control ratio of H 2 /HC by reducing it in the range of 0.0 to 1.0 by manipulating the speed of the steam driven recycle gas compressor. More preferably, the control of H 2 /HC ratio is optimized by reducing it in the range of 0.3 to 0.4.
  • the M-S configuration optimizes the catalyst circulation rate, by increasing it by 130 kg/hour.
  • the M-S configuration controls the coke on spent catalyst in the range of 3% to 6 %. More preferably, the M-S configuration controls the coke on spent catalyst in the range of 4.5% to 5.5%
  • the master controller is linked to the regenerator controller, such that the manipulated variable catalyst circulation (i.e. Master Lift Differential Pressure (DP)) of the master controller connects the master controller to the regeneration section slave controller.
  • DP Master Lift Differential Pressure
  • inferential For the master controller of the M-S configuration of the present invention, to control the coke on spent catalyst, it is imperative to first assess it. Hence, a powerful empirical tool known as inferential is implemented in order to predict the‘coke on spent catalyst’. In an embodiment, the inferential has been built using a rigorous regression tool, wherein inputs to the inferential are from both the reactor as well as the regeneration section.
  • the intent of the coke controller is to indicate that the coke on spent catalyst is at a certain value and the H 2 /HC ratio and the catalyst circulation rate have to be at a specified value to control the coke on spent catalyst in the desired range.
  • the APC system with the M-S configuration is designed without considering any time delay.
  • the M-S configuration controls the coke on the spent catalyst, using an online inferential built without any time lag.
  • the online bias updating of the spent catalyst coke inferential enables the APC system to capture change in metal dispersion, chloride on catalyst, extent of reduction, etc. which impact the complex process of coke laydown on catalyst.
  • an online inferential of heavy reformate octane is used to calculate heavy reformate octane barrel.
  • the online inferential is used by the APC system, to maintain heavy reformate octane and maximize heavy reformate octane barrel.
  • Online bias updation of the inferential enables the APC system to capture the change in reformer catalyst behavior due to factors like chloride water balance on the catalyst, platinum dispersion during catalyst rejuvenation in the regeneration section, equilibrium coke laydown on spent catalyst, catalyst aging, reduction in catalyst surface area, etc.
  • the regeneration controller is designed to control every aspect of catalyst regeneration starting from optimization of coke burn in the first bed of the regenerator, so that a minimum coke burning is maintained in the second bed of the regenerator at any point of time.
  • the regenerator controller maintains a higher coke burning rate in the first bed of the regenerator, in the range of 1 to l5°C higher than before implementation of APC. More preferably, the coke burning rate in the first bed of the regenerator is maintained in the range of 5 to l0°C higher than before the implementation of APC.
  • a minimum coke burning rate is maintained, by the regenerator controller, in the second bed of the regenerator in the range of 1 to 15 °C.
  • the minimum coke burning rate in the second bed of the regenerator is maintained at l0°C.
  • the controlling of a minimum coke burning rate in the second bed of the regenerator ensures that in case of variation in catalyst coke content, no coke slips unburned into the oxychlorination zone of the regenerator, thereby avoiding black burn and incomplete rejuvenation of catalyst, which in-tum affects the rate of desirable reaction and hence the octane barrel of the heavy reformate.
  • the regenerator controller comprises of the following as control variables:
  • the regenerator controller comprises of the following as manipulated variables (i) master catalyst lift differential pressure, which governs the catalyst circulation rate (ii) regeneration loop gas flow to primary bed (iii) primary burn inlet temperature (iv) primary bed inlet oxygen content (v) secondary bed inlet temperature (vi) secondary bed inlet oxygen content.
  • the regeneration controller controls catalyst rejuvenation.
  • the control of the catalyst rejuvenation comprises of controlling re-dispersion of noble metal on base catalyst and regaining activity by impregnation of huge amounts of chloride in a high oxygen atmosphere at a desired temperature and catalyst reduction to remove the water generated during carbon burn.
  • the regeneration controller controls (i) oxychlorination bed max. temperature (ii) calcination bed max. temperature as controlled variables (iii) oxychlorination zone electric heater power (iv) calcination zone electric heater power as the constraint variable by manipulating (i) oxychlorination zone electric heater outlet temperature (ii) calcination zone electric heater outlet temperature as constraint variables.
  • the regeneration controller controls the oxychlorination zone temperature at 10 to l5°C higher than before implementation of the-APC. More preferably, oxychlorination zone temperature is controlled at 13 to l4°C higher than before implementation of APC, as illustrated in fig. 16 of the present invention.
  • the fig. 16 shows that the oxychlorination zone temperature was controlled at 475°C before implementation of APC and 488°C after implementation of APC.
  • the regeneration controller controls the calcination zone temperature at 10 to 20°C higher than before implementation of APC. More preferably, calcination zone temperature is controlled at 13 to l4°C higher than before implementation of APC, as illustrated in fig. 17 of the present invention.
  • the fig. 17 shows that the calcination zone temperature was controlled at 477°C before implementation of APC and 49l°C after implementation of APC.
  • the regeneration controller controls the catalyst reduction temperature at 5°C higher than before implementation of the APC.
  • the fig. 18 of the present invention shows that the catalyst reduction temperature is controlled at a desired limit of 480°C.
  • the regenerator controller ensures that the oxygen content in the calcination zone of the regenerator is closer to the desired limit of 8% volume. As shown in the fig. 19 of the present invention, oxygen content in the calcination zone of the regenerator is controlled at least 1.0% to 1.5% volume higher than without implementation of APC.
  • the control of the oxychlorination, the calcination, and the reduction zone temperatures and oxygen in the calcination zone closer to their desired limit improves the rejuvenation of catalyst i.e. ensures proper re-dispersion of noble metal, platinum, on the base catalyst, impregnation of adequate amount of chloride in a high oxygen atmosphere, all of which in-tum increases heavy reformate octane barrel.
  • the regenerator controller controls the catalyst lift velocity in the range of 2.0 to 3.0 meters per second(m/s). More preferably, the catalyst lift velocities are reduced from around 3.0 - 3.5 m/s to the desired range of 2.0 m/s and maintain it consistently at that level. As shown in fig. 21 of the present invention, the catalyst lift velocity of one of the lift, lift 4 has been reduced from more than 10.0 m/s to 3.0 m/s.
  • the average catalyst make-up rate, in the CCR reformer, in the year 2016 was 248 kilograms per month before implementation of the APC and post the implementation of the APC in the regeneration section, the average catalyst make-up rate has been reduced to 231 kilograms per month.
  • the regenerator controller manipulates the outlet temperature of the electric heaters in the range of 5 to l0°C in the primary burn heater; 10 to l5°C in the reduction heater; 30 to 35°C in the oxychlorination zone heater; and 30 to 35°C in the calcination zone heater.
  • regenerator controller manipulates the regeneration loop gas flow in the range of 1000 to 4000 kg/hour.
  • the control / constraint variables of the reaction master controller comprise of heavy reformate octane barrel, heavy reformate octane, liquefied petroleum gas (LPG) and gas yield, I st reactor differential temperature, H 2 /HC ratio, reactor differential pressures (DP), NHT stripper bottom level, Plate Type heat exchanger Spray Bar DP, Plate Type heat exchanger Effluent outlet & Recycle gas DP, Plate Type heat exchanger Feed side DP, Plate Type heat exchanger Effluent side DP, and Plate Type heat exchanger Feed and Effluent side DP.
  • the manipulated variables of the reaction section master controller comprise of WAIT, separator pressure, recycle gas compressor speed, and reformer feed.
  • the manipulated variables of the reaction slave controller comprise of inlet temperatures of reactor 1 to 4.
  • the controlled / constraint variables of the reaction slave controller comprise of WAIT, skin temperature of heater 1 to 4, flue gas convention inlet temperature of heater 1 to 4, fuel gas pressure of heater 1 to 4, stack excess oxygen of heater 1 to 4, common flue gas convention inlet temperature of heater 1 to 4, and steam drum differential pressure.
  • the main product of CCR reformer is heavy reformate.
  • reformer operation is altered, once the octane analysis of heavy reformate is available which is typically once or twice in a twenty-four-hour period.
  • the action in the unit is unilaterally on reaction section operating severity, without acknowledging the impact on heavy reformate octane barrel.
  • the reaction controller of the present invention maximizes octane barrel of heavy reformate instead of only octane.
  • heavy reformate is a blend component of the refinery gasoline pool
  • the reaction controller operation translates into increase in production of gasoline from the refinery.
  • heavy reformate the octane barrel is calculated using an online inferential, an analytical tool, built in-house using regression.
  • the heavy reformate octane barrel would be maximized, by the reaction controller, by manipulating reformer severity i.e. reactor inlet temperature and separator pressure.
  • the reformer reaction section master controller generates a target WAIT based on its dependent (controlled) variable, heavy reformate octane barrel and the set point of the separator pressure. Therefore, in the reaction master controller‘WAIT’ is an independent variable.
  • the reactor controller varies the WAIT in the range of 8 tol0°C.
  • Fig. 7 of the present invention shows that the WAIT before implementation of APC was in the range of 536 to 538°C and the same after implementation of APC was in the range of 531 to 529°C.
  • the WAIT in-tum maintains heavy reformate octane in the range of 105-106 and is consistently maintaining a 1% to 2% higher heavy reformate yield.
  • the reaction slave controller Based on the translated value of the‘WAIT’, the reaction slave controller generates set-points for the four fired heaters outlet temperature to manipulate the fired heater fuel gas firing thereby controlling the WAIT.
  • the Fig. 9 of the present invention also illustrates that the fuel fired before implementation of APC was higher, approximately 161.3 MTPD (metric tonnes per day) and after implementation of the APC was lower, 147.0 MTPD.
  • the reactor controller consistently operates the unit at a lower fuel fired, at about 0.7 % wt. on feed lower after implementation of APC than before implementation of APC. Further, the fired heater outlet temperature being cascaded with fuel gas pressure, in the DCS level, controls the fired heater operation.
  • reaction slave controller manipulates the inlet temperature of the four reactors in series, considering fired heater constraints (eighteen number in all, for the four fired heaters) like tube skin temperature, flue gas convention inlet temperature, fuel gas pressure, excess oxygen and steam drum pressure. Further, reaction master controller maximizes reformer feed and optimizes H 2 /HC for which it gets a set point from the master controller.
  • the reactor controller optimizes the -ratio of H 2 /HC by reducing it in the range of 0 to 1 by manipulating the speed of the steam driven recycle gas compressor as shown in Fig. 11 of the present invention. More preferably, the H 2 /HC ratio is optimized in the range of 0.3 to 0.4. As illustrated in Fig. 10 of the present invention, the reactor controller optimizes unit operation from 2.6 to 2.2 by taking it closer to desired (1.8) H 2 /HC ratio. Further, Fig. 12 of the present invention shows that decrease in the H 2 /HC ratio reduces energy consumption and provides a lee-way for reformer feed maximization. In still another embodiment of the present invention, the reactor controller consistently operates at a lower steam consumption by about 65 MTPD.
  • the reactor controller consistently maintains heavy reformate yield at 1% to 2% higher than before implementation of APC. In another embodiment of the present invention, the reactor controller controls production of hydrogen product at a 3% - 5% higher rate than before implementation of APC. In yet another embodiment of the present invention, the reactor controller controls a higher heavy reformate and hydrogen yield even with 10% to 15% variation in feed naphthenes and aromatics content. In still another embodiment of the present invention, the controller controls methane content in the hydrogen product at the outlet of the PSA unit.
  • a reformer feed is characterized by its naphthenes (N) and aromatics (A) content i.e. N+A.
  • N naphthenes
  • A aromatics
  • the reaction controller in such a scenario would logically increase the operating severity i.e. WAIT. Therefore, to avoid increase in WAIT, the APC system of the present invention has the gas and the LPG yield as a constraint variable.
  • the heavy reformate octane would reduce and APC would increase operating severity i.e. WAIT, thus causing undesirable reverse action.
  • the I st Reactor Differential Temperature (DT) is implemented in the APC system to ensure that the APC does not take the reverse action.
  • the design features of compressors are incorporated and utilized in the reactor control strategy.
  • the recycle gas compressor is a steam driven centrifugal compressor while the net gas compressor is a 10 MW, three stage reciprocating compressors provided with a step less control. Normally load of the net gas compressor is manually increased or decreased based on change in feed quality, reactor operating severity etc. resulting in change in separator pressure. The recycle gas compressor load is also adjusted manually. Further, in order to control the ratio of H 2 /HC, the speed of the steam driven recycle gas compressor is manipulated by the APC. In yet another embodiment of the present invention, with the APC designed to change the reformer reactor operating severity and load of the steam driven recycle gas compressor, the flow to the net gas compressor varies. The step less control of the net gas compressor, operating in auto, ensures control of the separator pressure. VIII. Other APCs
  • the APC controllers comprising of coke, regeneration and reaction section, have also been implemented for control of (i) catalyst lift velocities (ii) recycle gas moisture (iii) optimization of refrigeration outlet temperature for improved recovery of hydrogen and LPG (iv) methane content in hydrogen product at the outlet of the Pressure Swing Adsorption (PSA) unit to maximize hydrogen production (v) catalyst chloride control (vi) corrosion control in regeneration washing drum loop.
  • PSA Pressure Swing Adsorption
  • the regeneration loop gas compressor is a reciprocating compressor with a flow control in its discharge.
  • the flow control governs the operation of the regeneration loop compressor as long as its discharge pressure is controlled. If the pressure increases above a certain specified value, the pressure becomes governing i.e. the pressure controls the operation of the compressor.
  • the APC has an intelligence to detect this change in operation in the DCS.
  • the manipulated variable is dropped out of the APC raising an alarm to draw panel person’s attention to the change in mode of operation from supervisory to supervisor.
  • the interlocks have been created so that in case of tripping of an equipment, the associated APC would trip, and an alarm will be generated to draw the attention of the panel person to the fact that the plant is out of supervisory control.
  • an interlock is incorporated, which drops the two oxygen analyzers, at primary and secondary bed inlet, out of the regenerator controller in case the oxygen content in the calcination zone falls below the desired level.
  • the regeneration controller trips.
  • the regeneration controller also trips in case of (a) shutdown valve associated with the master lift trips (b) regeneration goes from white burn to black burn.
  • the interlocks drop a particular manipulated variable from the APC in case of trip of its associated equipment / instrumentation like (a) burning bed inlet electric heater (b) oxychlorination bed inlet electric heater (c) calcination bed inlet electric heater (d) reduction chamber inlet electric heater (e) master lift shut down valve (f) lift 2 shutdown valve (g) lift 3 shutdown valve (h) lift 4 shutdown valve (i) lift 5 shutdown valve.
  • a burning bed inlet electric heater
  • calcination bed inlet electric heater calcination bed inlet electric heater
  • reduction chamber inlet electric heater e
  • master lift shut down valve f) lift 2 shutdown valve (g) lift 3 shutdown valve (h) lift 4 shutdown valve (i) lift 5 shutdown valve.
  • the interlocks have been created to drop the two oxygen analyzer (MV’s) - primary and secondary inlet - out of the APC in case (a) the air flow rate to the regenerator calcination zone is higher than a specified value (b) calcination zone oxygen analyzer is lower than a certain specified value (c) ratio of air flows to the secondary and primary bed is lower than a certain specified value, an indicator for erroneous oxygen analyzer(s). This would not only ensure that the APC does not try to control the process based on faulty analyzers but the panel person is alerted to get the analyzers re-calibrated / corrected.
  • PSA Pressure Swing Adsorption
  • the APC system of the present invention has been able to achieve this on a consistent basis, over a 14 month period, resulting in unit optimization irrespective of the feed quality.
  • the regeneration controller strategy was implemented after necessary tuning of DCS PID controllers, step test, model building and model acceptance test. Operation of the regeneration section APC, since December 2016, has shown consistent improvement in carbon burn, rejuvenation, reduction, water-chloride balance, lift velocity etc.:
  • the-APC has been successful in consistently operating at a higher (around 130 kilograms per hour) catalyst circulation rate.
  • the APC has also been able to increase the coke burning rate in the I st burning bed of the regenerator while keeping the bed and bed outlet temperatures within their operating limits, as shown in fig. 14 of the present invention. More the amount of coke being burnt in the regenerator (higher catalyst circulation rate) and higher the burning rate (higher I st bed differential temperature), more the scope for increasing reformer feed and reformer operating severity (reactor temperature) resulting in higher heavy reformate octane barrel generation.
  • the APC has been able to maintain a minimum burning rate in the 2 nd burning bed of the regenerator.
  • the 2 nd bed differential temperature has been increased from less than 5°C to more than l0°C, it ensures that no coke slips into the oxychlorination zone of the regenerator. No coke slippage reduces the possibility that the regenerator goes from‘white burn’ to‘black bum’, the unsteady state, where the catalyst is not rejuvenated and the heavy reformate octane barrel deteriorates.
  • Fig. 16 and fig. 17 of the present invention illustrates that the temperature in the oxychlorination and calcination zones of the regenerator were controlled l3°C to l4°C higher than before the implementation of APC.
  • the temperature in the reduction zone was also maintained closer to the desired limit of 480°C, as shown in the fig. 18 of the present invention. Further, fig. 19 of the present invention illustrates that the APC has also ensured that the oxygen content in the calcination zone of the regenerator is closer to the desired limit of 8% volume. Control of oxychlorination, calcination and reduction zone temperatures and oxygen in the calcination zone closer to their desired limit improves the rejuvenation of catalyst i.e. proper re-dispersion of noble metal, platinum, on the base catalyst, impregnation of adequate amount of chloride in a high oxygen atmosphere, all of which increases heavy reformate octane barrel. d) Reformer Recycle Gas Moisture Control
  • the APC of the present invention has been able to control recycle gas moisture in the desired range, unlike the spikes observed before the implementation of APC, as shown in the fig. 20 of the present invention.
  • the APC was able to control the water - chloride balance on the catalyst which governs the reforming reaction i.e. formation of desirable product - reformate - and control the production of undesirable byproducts like off gas and liquefied petroleum gas.
  • Fig. 21 of the present invention shows that the APC has been able to reduce the lift velocities from around 3.0 - 3.5 meters per second (m/s) to the desired range of 2.0 m/s and maintain it consistently at that level.
  • the lift velocity of one of the lifts, the 4 th one, which used to be more than 10.0 m/s was reduced to 3.0 m/s.
  • the average catalyst make-up rate, in the CCR reformer, in the year 2016 was 248 kilograms per month. Post the implementation of APC in the regeneration section, the average catalyst make-up rate has been reduced to 231 kilograms per month.

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Abstract

La présente invention concerne un système de commande de processus évolué (APC) pour un reformeur à régénération catalytique continue ayant une configuration maître-esclave pour commander le coke sur un catalyseur usé tout en optimisant le baril à indice d'octane de reformat lourd à l'aide d'inférences en ligne, tant pour la teneur en coke du catalyseur usé que pour l'indice d'octane du reformat lourd. En outre, la présente invention concerne un système APC pour un reformeur à régénération catalytique continue ayant une configuration maître-esclave, qui comprend un APC maître, un réacteur APC, et un régénérateur APC, le réacteur APC et le régénérateur APC étant reliés à l'APC maître.
EP18911402.8A 2018-03-29 2018-05-16 Commande de processus évolué dans un reformeur à régénération catalytique continue Withdrawn EP3774040A4 (fr)

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US3497449A (en) 1966-05-17 1970-02-24 Mobil Oil Corp Controlling a continuous process by concentration measurements
US3733476A (en) 1972-05-30 1973-05-15 Texaco Development Corp Means and method for automatically controlling the hydrogen to hydrocarbon mole ratio during the conversion of a hydrocarbon
ATE121120T1 (de) 1989-01-13 1995-04-15 Inst Francais Du Petrole Verfahren zur regenerierung eines katalysators zur reformierung oder zur herstellung von aromatischen kohlenwasserstoffen.
US5298155A (en) 1990-02-27 1994-03-29 Exxon Research & Engineering Co. Controlling yields and selectivity in a fluid catalytic cracker unit
US7291311B2 (en) 2002-03-15 2007-11-06 Institut Francais Du Petrole Process for controlling a moving bed combustion zone and its use
US20040099572A1 (en) 2002-11-26 2004-05-27 Martin Evans FCC catalyst injection system having closed loop control
US7351872B2 (en) 2004-05-21 2008-04-01 Exxonmobil Chemical Patents Inc. Process and draft control system for use in cracking a heavy hydrocarbon feedstock in a pyrolysis furnace
EA016421B1 (ru) * 2006-11-07 2012-04-30 Сауди Арабиан Ойл Компани Улучшенная система управления способом жесткого флюид-каталитического крекинга для максимизирования производства пропилена из нефтяного сырья
US8372770B2 (en) 2008-12-11 2013-02-12 Chevron U.S.A. Inc. Reformer regeneration process
US8815201B2 (en) 2012-05-22 2014-08-26 Chevron U.S.A. Inc. Process for regenerating a reforming catalyst
US10095200B2 (en) 2015-03-30 2018-10-09 Uop Llc System and method for improving performance of a chemical plant with a furnace

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US11318438B2 (en) 2022-05-03

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